This KO1 Mentored Research Scientist Award Nursiing application is designed to examine biochemical mechanisms of nocturnal urine production and nocturia in adults. Nocturia is commonly viewed as a benign condition more frequently seen in older populations. This is problematic because nocturia may place the older person at risk for injury from falls or may be a symptom of sleep related respiratory disorders such as obstructive sleep apnea (OSA), a serious but treatable condition. The primary aim of this study is to explore the biochemical mechanisms which affect nocturnal urine production manifested as nocturia. Nocturia can be attributed to a number of factors however this study will test an unexplored hypothesis. This supposition is that nocturia can occur as a result of the over production of urine evoked by sleep related respiratory disorders. This study will examine biochemical changes that occur during sleep and document how these events precipitate increased urine production. The secondary aim of this study is to characterize the potential causes and severity of nocturia in adults. It is well understood that increased frequency of urination at night can be caused by medical conditions such as diabetes, uriniary tract infection, and a lack of the normal diurnal rhythmicity of plasma vasopressin. This study will examine the potential contribution of other conditions such as daytime urinary frequency or symptoms of benign prostatic hypertrophy.